Unsaturated vicinal diol compounds are important compounds as raw materials of bioactive substance such as pharmaceuticals and agrichemicals, and monomers for production of functional polymers as described in U.S. Pat. No. 5,336,815. As methods for producing the unsaturated vicinal diol compound, a method comprising a reaction of an unsaturated epoxy compound with water in the presence of a sulfuric acid catalyst is described in U.S. Pat. No. 5,250,743. A method comprising a reaction of an unsaturated epoxy compound with water in the presence of an acidic resin is described in WO 91/15469. A method comprising a reaction of an unsaturated epoxy compound with water in the presence of rhenium oxide catalyst is described in DE 4429700. A method comprising a reaction of an unsaturated epoxy compound with water in the presence of titanium silicate or zirconium silicate is described in DE 4429699.